Regulation of 3phase alternator by zpf and asa methods 9. Distribution system voltage regulation and var compensation for different static load models article pdf available in international journal of electrical engineering education 374 october. In this experiment, the emf and mmf methods are used. When the load is thrown off voltage rise must be known because with the rise in voltage the insulation must be able to withstand this rise. Explain in detail, the mmf method for predetermining the voltage. Calculating voltage regulation of a synchronous machine determines the type of automatic voltage control equipment required for resisting the voltage changes. Regulation of three phase alternator by emf mmf and zpf posted by. No load and blocked rotor test on 3phase induction motor. Find out regulation of alternator by emf and mmf for full load at i unity p. Mar 28, 2015 because of the assumption of unsaturated magnetic circuit the regulation computed by this method will be less than the actual and hence this method of regulation is called optimistic method. Which of the method more accurate for determine the voltage. The regulation of a 3phase alternator may be predetermined by conducting the open circuit oc and the sort circuit sc tests. To calculate voltage regulation of synchronous machine by m. The voltage regulation of all alternator is defined as the rise in voltage when full load is removed field excitation and speed remaining the same divided by the rated terminal voltage.
Explain in detail, the methods of determining voltage regulation of an alternator. From occ the field current required to produce this normal voltage is 98 amps and is represented as i f 1 as shown in the phasor diagram. In this method both the reactance drops are replaced by their equivalent mmfs. This method is based on the separation of armature leakage reactance drop and the armature reaction effect. This mmf method is based on the results of open circuit test and short circuit test on an alternator. The following are the three methods which are used to predetermine the voltage regulation of smooth cylindrical type alternators synchronous impedance emf method ampereturn mmf method potier zpf method. Because of the assumption of unsaturated magnetic circuit the regulation computed by this method will be less than the actual and hence this method of regulation is called optimistic method.
For finding voltage regulation of an alternator, the method which gives most accurate result is a. Synchronous impedance method the synchronous impedance method or emf method is based on the concept of replacing the effect of armature reaction by an imaginary reactance. Blondels two reaction theory, phasor diagram, direct axis and quadrature axis synchronous reactances, power angle characteristics, slip test. The student has understood principle, construction, methods of. The mmf method replaces the effect of armature leakage reactance by an equivalent additional armature reaction mmf so that this mmf may be combined with the armature reaction mmf. Effective resistance per phase of the 3phase winding r open circuit characteristic occ at rated speedfrequency short circuit characteristic scc at rated speedfrequency 31.
Voltage regulation of alternator by mmf method and solved problems ampere turn method regulation of synchronous generator mmf. Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on youtube. The internally generated voltage in a single phase of a synchronous machine e a is not usually the voltage appearing at its terminals. Which of the method more accurate for determine the.
Voltage regulation of an alternator instrumentation tools. Regulations on 3phase salient pole alternator by slip test. Voltage regulation of alternator by mmfampere turn method. Slip test measurement of direct and quadrature axis reactance and predetermination of regulation of salient pole synchronous machines. The voltage regulation calculated using mmf method will always be lower than actual voltage regulation of an alternator. Write down the equation for frequency of emf induced in an alternator. Explain any one of the indirect methods to determine voltage regulation. Blondels two reaction theory, phasor diagram, direct axis and quadrature axis synchronous reactances, power angle characteristics, slip. Potier method of predetermining the voltage regulation of an. Zs at any load value can be determined so voltage regulation of alternator at any load condition and load power factor can be calculated. Jun 11, 2015 voltage regulation of synchronous generator by mmf method. Voltage regulation of alternator emf and mmf methods. The open circuit characteristic is the graph of the circuit.
Electrical machines ii unit i alternator basic principle a. Electrical machines questions and answers synchronous generators voltage regulation of an alternator. Automatic voltage regulator r610 instruction manual. Performance of synchronous generator connected to infinite bus, under. Starting with zero field current, increase the field current gradually and cautiously till. Voltage regulation of an alternator is defined as the change in terminal voltage from no load to full load expressed as a percentage of rated voltage when the load at a given power factor is removed with out change in speed and excitation. Pdf a wide regulated series hybrid excitation alternator. Perform no load and short circuit tests on a threephase alternator. Why is the mmf method of estimating the voltage regulation considered as the optimistic method. They also consist of an armature winding and a magnetic field. Hence regulation of the alternator at any load condition and load power factor can be determined. Potier method of predetermining the voltage regulation of an alternator.
Voltage regulation of alternator by mmf method and solved. Synchronization of two three phase alternators, by a synchroscope method b three dark lamp method c two bright one dark lamp method 6. Regulation of 3phase alternator by emf and mmf methods. Mmf method of voltage regulation its phasor diagram circuit. Jun 04, 2015 the voltage regulation of an alternator is defined as the rise in voltage when fullload is removed field excitation and speed remaining the same divided by the rated terminal voltage. Name two methods used to determine voltage regulation of alternators. The reasons that the armature voltage e a is not equal to the output voltage v are. Aug 22, 2017 the voltage regulation calculated using mmf method will always be lower than actual voltage regulation of an alternator. Regulation of three phase alternator by emf mmf and zpf page link. Why is the mmf method of estimating the voltage regulation is considered as the. Why is the mmf method of finding alternator voltage. It equals to the output voltage v only when there is no armature current in the machine.
Which one of the following methods gives more accurate result for determination of voltage regulation of an alternator. Mmf method is used for determining the voltage regulation of an alternator or synchronous generator is also called ampere turns. This is more accurate than the emf and mmf methods. Electrical machines short answers instrumentation tools. Stator the stator or armature is an iron ring, formed of laminations of silicon steel with. Voltage regulation of alternator by mmf method requires mmf which is a product of field currenti and number of turnsn of field winding for two separate purposes. For calculating the regulation, the synchronous method requires the following data. Voltage regulation of alternator emf and mmf methods youtube.
In the operation of an alternator, the armature resistance drop ir a and armature leakage reactance drop ix l are actually emf quantities while the armature reaction is basically mmf quantity. Voltage regulation of an alternator by emf and mmf methods. In electrical engineering, particularly power engineering, voltage regulation is a measure of change in the voltage magnitude between the sending and receiving end of a component, such as a transmission or distribution line. C is a plot of the armature terminal voltage as a function of field current with a symmetrical three phase shortcircuit applied across the armature terminals with the machine running at rated speed. The method is based on the results of open circuit test and short circuit test on an alternator. Mmf method for determining voltage regulation of alternator. Using the details it is possible determine the regulation. How to draw the graph for mmf method i draw the open. The voltage regulation of alternator at 100 a load at 0.
The following are the three methods which are used to predetermine the voltage regulation of smooth cylindrical type alternators. Voltage regulation of an alternator by emf and mmf method. Methods to determine voltage regulation of alternator. A wide regulated series hybrid excitation alternator article pdf available in iet electric power applications 123 december 2017 with 73 reads how we measure reads.
When we supply the magnetizing current by dc shunt generator through two slip rings in recent alternators, they use electronic starting system instead of slip rings and commutators because the field magnets are rotating. Short questions and answers ee1251 electrical machines ii. To calculate the voltage regulation by mmf method, the following information is required. Methods to determine voltage regulation synchronous impedance method mmf method zero power factor method. For any synchronous generator or alternator, mmf is required, which is a product of. Or the numerical value of the regulation is defined as the percentage rise in voltage when full load at the specified powerfactor is switched off with speed. Measure the resistance of the stator armature winding of alternator. Mmf method of voltage regulation its phasor diagram.
Voltage equation per phase will be similar in to the single phase alternator. Voltage regulation of synchronous generator or alternator. Voltage regulation of synchronous machine alternator by. This method of determining the regulation of an alternator is also. Voltage regulation of a synchronous generator direct. Potier method of predetermining the voltage regulation of. It must have an mmf which is necessary to induce the rated terminal voltage on open circuit condition.
Which method gives the result nearer to the actual value. When operating at 60 hz, terminals 5a and 6 should be connected to each other in order to keep the low frequency protection correctly regulated. Where ra armature resistance of alternator per phase calculate the excitation emf eo and voltage regulation for fullload and 1. If which would generate a voltage e0 under no load conditions of the alternator. Mention the methods by which voltage regulation can be determined. Zero power factorzpf or potier triangle method for. The main advantages of this method is the value of synchronous impedance z s for any load condition can be calculated. Phasor diagram, voltage regulation using synchronous impedance and potier triangle method. Voltage regulation of alternator emf and mmf methods duration. Pdf distribution system voltage regulation and var.
Normally for voltage regulation calculation, we use methods like. The mmf method replaces the effect of armature leakage reactance by an. Actual load need not be connected to the alternator and hence method can be used for very high capacity alternators. Voltage regulation of synchronous machines alternator by. Emf equation of an alternator and ac generator electrical. To start induction motor by rotor resistance starter 8. Regulation of 3phase alternator by zpf and asa methods. A single phase, 2000 v alternator has armature resistance and reactance of 0. May 28, 2018 voltage regulation of alternator emf and mmf methods. Apr 20, 2016 normally for voltage regulation calculation, we use methods like. The methods employed for determination of regulation are emf or synchronous impedance method, mmf or ampere turns method and the zpf or potier triangle method. For any synchronous generator or alternator, mmf is required, which is a. Name the various methods for predetermining the voltage regulation of 3phase alternator.
An alternator or ac generator dynamo is a device which convert mechanical energy to electrical energy. The current range of the instrument should be about 2550 % more than the full load current of the alternator. Synchronous impedance method armature turn or mmf method zero pf or potier method synchronous impedance method gives result which is higher than the original value. Performance of synchronous generator connected to infinite bus, under constant power. F regulation cp1950120 c51950121 nt1950120a0494 basic optional note. Home machines voltage regulation of synchronous generator or alternator voltage regulation of synchronous generator or alternator april 21, 2020 we know that that the terminal voltage of a synchronous generator changes on application of load across its output terminals. Also comment on the merit and demerits of the method. Voltage regulation of a synchronous generator the voltage regulation of a synchronous generator is the rise in voltage at the terminals when the load is reduced from full load rated value to zero, speed and field current remaining constant. To calculate the voltage regulation by mmf method, the following information is. Synchronous machines notes part2 electric equipment. Similar to emf method oc and sc characteristics are used for the determination of regulation by mmf method. Requirements for calculating voltage regulation by emf method or synchronous impedance method. Mmf method is used for determining the voltage regulation of an alternator or synchronous generator is also called ampere turns method or rotherts mmf method. But there is one important difference between the two.
Voltage regulation of alternator and solved example youtube. Voltage regulation of alternator emf and mmf methods smile and learn. Starting with zero field current, increase the field current gradually and cautiously till rated current flows in the armature. The regulation curve is drawn between regulation and power factor viva questions. Figure shows the complete phasor diagram for the mmf method. Speed control of dc motor by armature voltage control and flux control. This zero power factor zpf method is used to determine the voltage regulation of synchronous generator or alternator. Voltage regulation describes the ability of a system to provide near constant voltage over a wide range of load conditions. In this method also it is assumed that the magnetic circuit is unsaturated.
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